Re: [PATCH] clocksource: Use GENMASK_ULL in definition of CLOCKSOURCE_MASK

Matthias Kaehlcke
2017-04-17T16:57:12Z

Hi Dmitry,

El Fri, Apr 14, 2017 at 09:02:03PM -0700 Dmitry Torokhov ha dit:

> On Tue, Apr 11, 2017 at 12:17 PM, Matthias Kaehlcke <mka@chromium.org> wrote:
> > Besides reusing existing code this removes the special case handling
> > for 64-bit masks, which causes clang to raise a shift count overflow
> > warning due to https://bugs.llvm.org//show_bug.cgi?id=10030.
> >
> > Suggested-by: Dmitry Torokhov <dtor@chromium.org>
> > Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
> > ---
> > include/linux/clocksource.h | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
> > index cfc75848a35d..06e604b9e9dc 100644
> > --- a/include/linux/clocksource.h
> > +++ b/include/linux/clocksource.h
> > @@ -120,7 +120,7 @@ struct clocksource {
> > #define CLOCK_SOURCE_RESELECT 0x100
> >
> > /* simplify initialization of mask field */
> > -#define CLOCKSOURCE_MASK(bits) (u64)((bits) < 64 ? ((1ULL<<(bits))-1) : -1)
> > +#define CLOCKSOURCE_MASK(bits) (u64)GENMASK_ULL((bits) - 1, 0)
>
> I do not think cast to u64 is needed for GENMASK_ULL.

Indeed, it is not needed, I will update the patch

Thanks!

Matthias